Table clamp for machine tools



Nov. 28, 1950 J. M. WALTR 2,532,046

TABLE CLAMP FOR MACHINE TOOLS 'iled Nov. 15, 194e Ill"HIII In" 2 Sheets-Sheet 1 Nov. 28, 1950 .1. M. WALTER 2,532,046

TABLE CLAMP FOR MACHINE TOOLS Filed NOV. l5, 1946 2 Sheets-Sheet 2 INVENTOR. dbf/N M MA1-EQ.

ATTORNEYS.

Patented Nov. 28, `1950 TABLE CLAMP FOR MACHINE TOOLS John M. Walter, Cincinnati, Ohio, assigner to The G. A. Gray Company,

corporation of Ohio Cincinnati, Ohio, a

Application November 15, 1946, serial No. 709,980

(o1. 18s-c7) 7 Claims.

My invention relates to devices for clamping a sliding table in machine tools in a selected position. As an example of a point of use of such a clamping or position retaining device, I have applied the device to the table of a planer type machine used for boring, drilling, and milling. In such a machine the work is secured to a table and can be moved transverse to the tools bythe actuation of the table. It is, however, desirable in many operations that the work be immovable and the tools be moved into the work, in which case it is desirable to lock the table immovably, and by power.

In the past, so far as I am advised, such clamping has been provided for by forcing the table down tightly on its supportingv ways by some means or other, but this is not fully effective because the surface against which clamping is exerted is a precision surface lubricated under pressure, thus tending to minimize the friction needed to hold the table immovable against heavy stress exerted against the work clamped thereon.

It is the object of my invention to avoid this diiliculty and to that end I form an element to be clamped on the table itself, preferably integrally, and apply braking pressure to this element. In the preferred form this element is so arranged that the braking pressure as applied not only grips the element laterally but also tends to force the table downwardly somewhat.

Objects are to make such a clamp very strong and sturdy, and provide for adjustability thereof, and simple mode of operation.

An example of the novel device, selected for the purpose of Villustrating the inventive concept, has been shown in the drawings, but from the appended claims it will be noted that the invention is not limited to the details of this construction.

In. the drawings:

Figure 1 is a side elevation illustrating the clamp and power operating means therefor.

Figure 2 is a section on the line 2-2 of Figure 1.

In the illustrated device a bed is indicated at I, and a work supporting table at 2. Beneath the overhang of the table where it projects along one side over the sides, I form integrally a longitudinal dovetail shaped depending rib 2a. This rib or rail could Ibe secured to the overhang in other ways but it is preferred and quite simple to make it integral. The clamping device engages this rail, and is secured to the bed.

While variations in particular clamping devices are within the scope of my invention, I have shown one which consists of twoplates 3, and having legs 5, which are secured together and to the side `of the bed as by bolts 6. The upper ends of the plates are formed with undercut edges 1, where they lie one on each side of the dovetail depending rail. Preferably a suitable brake lining as illustrated at 8 is secured at their undercut edges. Y

The plate 4 is shown as having a channel 9 therein in which is slidably held a rack bar I0, shaped as a rod and Vhaving rack teeth Il on the upper face thereof. Both of the plates are provided with holes I2 and I3 respectively, in which is supported a pinion I4, on a pin l5, in bearings I6.

A preferably integral structure consisting of a gear II with spindle portions I8 and I9, is mounted in bearings 2i) in the two clamp plates, with the gear lying between the two plates as does the pinion I4. The spindle portion I9 is tted with a threaded nipple 2| which can be adjusted on the spindle end and held in place with a set screw 22. The nipple bears on a bearing race 23, retaining ball bearings between it and a raceway 24. The raceway 24 engages the base of the socket in the clamping plate 4 in which the nipple is located. This construction provides for adjustment of the clamping action of the two plates l3 and 4.

On the other spindle end I8 the threaded portion I8@ thereof engages within a nut 25, which nut has a seat on a bearing ring 26 that lies in the base of the socket in plate 3 in which the nut is located. This nut is arranged to be slidable but not rotatable in the socket in the side plate 3, by having two fiat faces engaging in grooves in the socket (not shown), and hence when the gear II is rotated the nut 25 will be drawn toward the gear, the spindle being provided with -a thrust bearing by the nipple and bearing structure on its other spindle end.

The two plates are constrained toward each other by the gear and spindle arrangement described, and their natural resilience will tend to spread them somewhat. Thus to apply braking and clamping pressure to the dovetail rail on the table of the machine, the gear is rotated in one direction which pulls the two sides of the clamp together and grips the dovetail rail. To release the clamp the gear is rotated in the opposite direction which releases gripping pressure by the natural resilience of the structure. The effect of the clamp is to engage the two sides of the dovepower means here shown to be a hydraulic device,A the piston rod 2l whereof is connected to the rack' bar. 'I'his may be by means of a universal -joint as indicated at 28, which may be of any desired construction.

Having thus described my invention, what Il claim as new and desire to secure by Letters Patent is:

l. Mechanisms for clamping, comprising a rail element moving with the table on a machine tool bed, a pair of plates arranged to engage the oppositesid'es-cf said rail element, a spindle conn nected to engageeach ofthe-plates, saidI spindlevv engagingriat ieast oneof the plates with a threaded" connection, a gear for rotating said spindley mounted thereon betweensaid plates, andaracirA having sliding engagement with one of said-plates atleast and meshing with said gear, for actuating said mechanism.

2. The combination of claim 1 in which the spindle is provided with a thrust bearing'on one of said plates such that the other plate has a threaded connection with said spindle.

3. The combination of` claim l in which the saidv thrust bearing is adjustable on-the spindle axially thereof.

4. A brake applying mechanism ccmprisinga pair of plates the edges of which are sha-pedto engage the sides'of a member projecting between them, a bed with respect to which saidmem'ber is movable, means at the other end of said plates for bolting them to said bed, a rack bar slidably supported between said plates, a gear supported between said plates and having driving relation to said rack bar, said gear having a spindle, one end of which is rotatably supported in one of the plates, and the other end of which is threaded and equipped with a nut bearing on the other of the twoplates.

5: The combination of claim 4 in which the rotatable support of the spindle in one of said plates comprises a thimble threaded on the spindlefand having an antifriction bearing on the said plate.

6. The combination of claim 4 in which the rotatable support of the spindle in one of said plates comprises -a thimble threaded on the spindle, andl having a set screw to lock it in adjusted threaded position on said spindle, said thimble havinga bearing on the plate,

7. The combination of claim 4 in which the rotatable. supportxof. the spindle inA onetof said plates .comprises a. thimble .threadedon theaspin.-L dle, and having a set screw. to lockit in adjusted'.-l threaded position on saidY spindle, saidc thimble; having an. antifrictionbearingagainstthe plate..

JOHN M; `WAIJI'EH..

REFERENCES GTED rEhe following references a-re of record irrthe file of'this patent:

Number Name Date 600,324 Strub Mar. 8, 18'98 638,695 Beeley Dec. 12; 1899',v

1,511,231 Miles et al Oct. 14, 1924 1,930,567. Shaw Octl 17T,l 1933 2,291,665' Turrettini Aug. 4, 1942i 2,296,954' Schneider Sept. 29, 1942 2,349,004 Richards May 14, 1944'. 

